It is well-known that patients in hospitals often develop deep vein thrombosis or blood clots in the leg veins over extended periods of hospital stay. This is particularly prevalent in elderly weak patients and those undergoing major surgery. It has been known that this condition can be controlled or alleviated by applying intermittent pressure to the patient's legs to assist in blood circulation. Many devices have been proposed, such as compression boots and other inflation tube devices. The prior boots had the disadvantage of being very cumbersome and substantially restricting the movement of the patient. To overcome this, it has been proposed by others to use an elastic stocking with an internal panel creating a pocket within the stocking for receiving an inflatable pulsating bladder. Such a device is schematically shown in cross-section by FIG. 1, wherein dotted lines are used to show both the stretchable outer stocking layer and the inner panel.
In the prior art pulsatile elastic stocking of FIG. 1, the stocking had to be sufficiently stretchable for easy donning and yet be sufficiently inelastic at an upper limit to provide sufficient compressive forces against the leg when the bladder was inflated. These competing functions made it difficult to provide the precise stretch-ability in the elastic stocking such that a stocking could fit a substantial range of patient leg sizes and shapes.